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Medical Definition of Tunica muscularis gastrica
1. Muscular tunic of the stomach, consisting of smooth muscles arranged in three fairly well defined layers: an outer longitudinal layer, continuous with that of the oesophagus but dividing at the cardia into two bands which run along the greater and lesser curvatures, leaving the middle areas of the anterior and posterior walls devoid of longitudinal fibres, and then coalescing in the pyloric region into a complete layer which is continuous with the longitudinal coat of the duodenum. The middle circular layer is most complete and strongest, continuous with the circular layer of the oesophagus at the cardia; it thickens progressively toward the pylorus, ultimately forming the muscular ring of the pyloric sphincter. The inner, oblique layer is unique to the stomach and is most strongly developed in the fundic region and absent along the lesser curvature. This absence contributes to the formation of the "gastric canal." See: oblique fibres of stomach. Synonym: tunica muscularis gastrica, tunica muscularis ventriculi. (05 Mar 2000)